With the recent explosion of smart mobile devices and location-based services/applications, such as location-based advertising, product finding, and friend tracking, etc., it has become increasingly important to provide reliable and accurate indoor location sensing. can enable a number of new mobile applications.
Various attempts have been made to achieve indoor location sensing by piggy-backing on existing wireless network systems. For example, with the proliferation of WiFi networks, indoor localization sensing that utilizes WiFi signal strength and/or WiFi timing-based trilateration techniques have been developed. However, while such indoor localization techniques do not require additional infrastructure, they may not guarantee the required accuracy due to the large variation of signal strength in indoor environments. Moreover, because WiFi signals can easily penetrate through walls, it may be difficult to identify different rooms/spaces that are adjacent to each other. As such, wireless network-based indoor localization techniques are not without accuracy and/or reliability issues.